Turbine blade



April 9, 1929. R. scHlLLlNG TURBINE BLADE Filed sept. 4, 1925 TML Gl mMms RL H Ou. N T# R mc O Ww m l. w V| @Bm Patented Apr. 9, 1929.

UNITED STATES 1,708,402 PATENT OFFICE.

'RUDOLPH sCHILLINa/OF wooDsIDE, CALIFORNIA, AssIGNOR 'ro HOLzWAR'rII GAsTUBBINE co., or SAN FRANCISCO, CALIFORNIA, A CORPORATION or DELAWARE.

TURBINE BLADE.

lApplication led September 4, 1926. Serial No. 133,566.

-My present invention relates to turbine blades, and particularly toconstructions in which such blades are in contact with a hotdrivingmedium, such as combustion gases under pressure, and also wlth a coolingmedium. My invention is` applicable to turbines having partitionedblades whereby there arev produced an inner path andan Outer path, oneof which is used for the combustion gases or other hot driving medium,and the other. for the cooling medium, for instance steam. As regardsthe absorption of heat by the blades vfrom the hot driving medium,

this depends chiefiy upon the area of the surface with which such mediumcomes in contact. The removal yor dissipation of the heat thus absorbed,however, is determined largely by the cross section of the blades, sincethis is a measure of the path afforded for such dissipation. Since it ispossible to increase the cross section of the blades without materiallyincreasing their surface, I am enabled to obtain a higher rate of heatdis sipation without altering the rate of heat absorption, and as aresult, a more eiiicient cooling of the blades.

I have found it desirable to employ a relatively large diameter for therotor body to which' the inner ends of the rotor blades are fastened andto use a relatively low number of revolutions. The cooled portions ofthe rotor blades are preferably made of' approximately the same lengthas the blade portions in contact with the hot combustion gases, and theexit angle at the cooled blade portion is preferably smaller than theexit angle at the hot blade portions. By causing the hot combustiongases to travel through the inner blade path, and the cooling mediumthrough the outer blade path, I secure a double cooling effect, sincethe outer portions of the blades are in contact with a cooling medium,while their inner ends are secured to a rotor drum or body whichdissipates the heat, particularly if this drum is cooled Vby passingsteam or some other suitable AThe rotor of the turbine has a body ordrum 10 to which are secured the inner ends or feet of the rotor'blades11. 'lhe latter are preferably made of greater thickness at their innerportions than toward their ends, so as to facilitate the conduction andtransfer of heat from the rotor blades to the drum, which is preferablycooled internally, as set forth hereinafter. About midway between theirends, the blades are provid-ed with partitions 12 bridging the spacesbetween adjacent blades and forming part of a cylindrical wall whichsubdivides the blade channels into an inner path and an outer pathfurther removed from the center of the rotor than said inner path. Thedriving medium, preferably hot combustion gases under pressure, obtainedby the-explosion of a mixture of air and fuel, is discharged against theinner portions of the rotor blades 11 from stationary nozzles 13. In theparticular embodiment shown, the rotor has two sets of blades 11 actedupon successively by the driving medium, and in this case stationaryso-called, reversing blades 14 are projected inwardly from the casing 15between the two sets of rotor blades, and these reversing stator blades14 are provided with partitions 16 in line with the partitions 12 of therotor blades and in as close proximity thereto as possible, so as toobtain a practically tight joint between the rotating partitions 12 andthe stationary partitions 1G and keep the driving medium travelingthrough the inner path separate from the cooling medium which passes incontact with the outer portions of the blades 11, 14. This coolingmedium, which may be steam (the temperature of such steam being lowerthan that of the combustion gases) is discharged against the outerportions of the rotor blades 11' of the first set, from nozzles 17receiving their supply through a pipe 18. After passing in Contact withthe outer portions of the rotor blades of both sets and of the reversingblades 14, and thus cooling all the blades, such steam, as it issuesfrom the last set of rotor blades, may be conducted, in full or in partas by a pipe 19, to the interior of the rotor vdrum 10 so as to cool thelatter and the inner rotor blade portions which are in contacttherewith; the steam finally passes out at 20. The balance of the steammay leave at exit pipe 21. The radial length of the outer rotor bladeportions is approximately the same as the radial length of the innerblade portions. The blade portions which come in contact with the hotcombustion gases are preferably made with a greater exit angle than theblade portions `which come in contact with the steam or othcrcoolingmedium as shown in Figs. 3 and 4. The purpose of this arrangement is tocause the cooling medium' to come in contact With a heat-absorbingsurface which is about as large as the heat-absorbing surface in contactwith the combustion gases.

While li have referred to the iiuid medium ot' lower temperature as acooling medium (i. e. the steam) it will be obvious that such coolingmedium, While of. a lower temperature than the combustion gases, may yetbe ot such pressure as to be capable of performing Work in the turbine,the steam, or its equivalent, beingsuperheated by the coinbustion gasesthrough the medium of the blades, the gases thus acting as asuperheating medium.-

Various changes in the specific forms shown and described may be madeWithin the scope of the claims Without departing from the spirit of myinvention.

I claim:

1. A turbine comprising a rotor having blades partitioned to form aninner path and an outer pat-h beyond said inner path, in combinationwith devices for Adirecting a cooling medium into one 'of said paths anda hot driving medium into the other path, and with a rotor body to whichsaid blades are attached at one end, the thickness of the bladesincreasingv toward their lattached ends.

2. A turbine comprising a rotor having blades partitioned to form aninner path and an outer path beyond said inner path,

in combination with devices for directing a cooling medium into one ofsaid paths and a hot driving medunn into the other path,

the exit angle of the blades being greater at one of said paths than atthe other.

3. turbine comprising rotor blades partitioned to form an inner path andan outer path, a hollow rotor body to which the inner ends of saidblades are secured, devices for directing a cooling medium into one ofsaid paths and a hot driving medium in the other path, and a connectionfor leading the cooling medium after its passage in reversing bladesarranged between said sets of rotorblades and artitioned correspondinglythereto, and evices for' directing a cooling medium into one of saidpaths and the hot driving medium into the other path.

5. ln a turbine, a hollow rotor body, rotor blades each having its innerend secured to said rotor body, said blades being arranged in two setsand partitioned to form an inner path and an outer path beyond saidinner path, the thickness of said blades increasing toward said rotorbody, stationary reversing blades arranged between said sets of rotorblades and partitioned correspondingly thereto, devices for directing acooling medium into one of said paths and the hot driving medium intothe other path, and a connection for conveying the cooling medium afterit has passed in contact with the said blades, into the said hollowrotor body to cool the same internally.

In testimony whereof I have hereunto set my hand.

RUDOLPH SCHILLNG.

